From: Simon Horman <horms@kernel.org>
To: David Howells <dhowells@redhat.com>
Cc: Christian Brauner <christian@brauner.io>,
Steve French <smfrench@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
Jeff Layton <jlayton@kernel.org>,
Gao Xiang <hsiangkao@linux.alibaba.com>,
Dominique Martinet <asmadeus@codewreck.org>,
Marc Dionne <marc.dionne@auristor.com>,
Paulo Alcantara <pc@manguebit.com>,
Shyam Prasad N <sprasad@microsoft.com>,
Tom Talpey <tom@talpey.com>,
Eric Van Hensbergen <ericvh@kernel.org>,
Ilya Dryomov <idryomov@gmail.com>,
netfs@lists.linux.dev, linux-afs@lists.infradead.org,
linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org,
ceph-devel@vger.kernel.org, v9fs@lists.linux.dev,
linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 18/24] netfs: Speed up buffered reading
Date: Fri, 2 Aug 2024 15:44:05 +0100 [thread overview]
Message-ID: <20240802144405.GD2504122@kernel.org> (raw)
In-Reply-To: <117846.1722608282@warthog.procyon.org.uk>
On Fri, Aug 02, 2024 at 03:18:02PM +0100, David Howells wrote:
> Simon Horman <horms@kernel.org> wrote:
>
> > If the code ever reaches this line, then slice will be used
> > uninitialised below.
>
> It can't actually happen (or, at least, it shouldn't). There are only three
> ways of obtaining data: downloading from the server
> (NETFS_DOWNLOAD_FROM_SERVER), reading from the cache (NETFS_READ_FROM_CACHE)
> and just clearing space (NETFS_FILL_WITH_ZEROES); each of those has its own
> if-statement that will set 'slice' or will switch the source to a different
> type that will set 'slice'.
>
> The problem is that the compiler doesn't know this.
>
> The check for NETFS_INVALID_READ is there just in case. Possibly:
>
> if (source == NETFS_INVALID_READ)
> break;
>
> could be replaced with a WARN_ON_ONCE() and an unconditional break.
Thanks, I think that should make the compiler happy without
significantly altering the flow or readability of the code.
next prev parent reply other threads:[~2024-08-02 14:44 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-29 16:19 [PATCH 00/24] netfs: Read/write improvements David Howells
2024-07-29 16:19 ` [PATCH 01/24] fs/netfs/fscache_cookie: add missing "n_accesses" check David Howells
2024-07-29 16:19 ` [PATCH 02/24] cachefiles: Fix non-taking of sb_writers around set/removexattr David Howells
2024-07-29 16:19 ` [PATCH 03/24] netfs: Adjust labels in /proc/fs/netfs/stats David Howells
2024-07-29 16:19 ` [PATCH 04/24] netfs: Record contention stats for writeback lock David Howells
2024-07-29 16:19 ` [PATCH 05/24] netfs: Reduce number of conditional branches in netfs_perform_write() David Howells
2024-07-29 16:19 ` [PATCH 06/24] netfs, cifs: Move CIFS_INO_MODIFIED_ATTR to netfs_inode David Howells
2024-07-29 16:19 ` [PATCH 07/24] netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream David Howells
2024-07-29 16:19 ` [PATCH 08/24] netfs: Reserve netfs_sreq_source 0 as unset/unknown David Howells
2024-07-29 16:19 ` [PATCH 09/24] netfs: Remove NETFS_COPY_TO_CACHE David Howells
2024-07-29 16:19 ` [PATCH 10/24] netfs: Set the request work function upon allocation David Howells
2024-07-29 16:19 ` [PATCH 11/24] netfs: Use bh-disabling spinlocks for rreq->lock David Howells
2024-07-29 16:19 ` [PATCH 12/24] mm: Define struct folio_queue and ITER_FOLIOQ to handle a sequence of folios David Howells
2024-07-29 16:19 ` [PATCH 13/24] cifs: Provide the capability to extract from ITER_FOLIOQ to RDMA SGEs David Howells
2024-07-29 16:19 ` [PATCH 14/24] netfs: Use new folio_queue data type and iterator instead of xarray iter David Howells
2024-07-29 16:19 ` [PATCH 15/24] netfs: Provide an iterator-reset function David Howells
2024-07-29 16:19 ` [PATCH 16/24] netfs: Simplify the writeback code David Howells
2024-07-29 16:19 ` [PATCH 17/24] afs: Make read subreqs async David Howells
2024-07-29 16:19 ` [PATCH 18/24] netfs: Speed up buffered reading David Howells
2024-07-31 19:07 ` Simon Horman
2024-08-01 18:53 ` Nathan Chancellor
2024-08-02 14:18 ` David Howells
2024-08-02 14:44 ` Simon Horman [this message]
2024-07-29 16:19 ` [PATCH 19/24] netfs: Remove fs/netfs/io.c David Howells
2024-07-29 16:19 ` [PATCH 20/24] cachefiles, netfs: Fix write to partial block at EOF David Howells
2024-07-29 16:19 ` [PATCH 21/24] netfs: Cancel dirty folios that have no storage destination David Howells
2024-07-29 16:19 ` [PATCH 22/24] cifs: Use iterate_and_advance*() routines directly for hashing David Howells
2024-07-29 16:19 ` [PATCH 23/24] cifs: Switch crypto buffer to use a folio_queue rather than an xarray David Howells
2024-07-29 16:19 ` [PATCH 24/24] cifs: Don't support ITER_XARRAY David Howells
2024-07-30 10:36 ` (subset) [PATCH 00/24] netfs: Read/write improvements Christian Brauner
2024-07-30 10:38 ` Christian Brauner
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